Time-limit circuit-breaker.



W. FELLENBERG.

TIME LIMIT CIRCUIT BREAKER.

APPLICATION FILED AUG. 29, 1907.

Patented Apr. 27, 1909.

151 JNVE'ZYTUR (a: WZLHELM FELLENBEHG.

MTAE'SSESf 1 UNITED STATES PATENT FFYQEF.

WILlzIELM FEL LENBERG, F CHARLOTTENBURG, GERMANY, ASSIGNOR TO GENERALELEG- I TRIO COMPANY, A CORPORATION OF NEW YORK.

TIME-LIMIT GIRCUIT-IBREAKE R.

Specification of Letters Patent.

Patented Apr-i127,- 1909.

. Application filed August 29, 1907. Serial No. 390,605.

. breakers, and more particularly to circuit breakers which open. onlyafter an abnormal current has persisted for a predetermined length oftime.

Time limit devices which secure a time lag by the use of a thermostaticdevice such as a hot Wire ,or' expansion bar heated by the flow ofcurrent are'very simple and etiective and have the advantage that theyare affected only by the amount of current which flows through themregardless of its frequency or wave form. One disadvantage is that'abreaker controlled by a thermostatic time limit device cannot be resetwhile the device is hot, and another arises from the fact that a flow ofcurrent through an expansion bar causes it to elongate at a constantlydecreasing rate, so that while the greater part of the elongation takesplace in a comparatively short period of time, the 30 bar does not reachits maximum elongation until after a very considerable period of timehas elapsed. Thermostatic trip mechanisms can therefore be used. onlywhere the circuit breaker .trips on an overload considerably greaterthan normal, since if an expansion bar is designed to expand enough totrip the circuit breaker within a reason- Mable time limit at a currentfive or ten per- "cent greater than normal, it will very graduallyexpand at normal current until eventually it will trip the circuitbreaker although the current is only normal. Another disadvantage of asingleexpansion bar used for .a. time limit trip device for circuitbreakers is that the amount of current flowing through the bar cannot bechanged without changing the time lag of the device, andjit is oftendesirable to alter the amount of CIHIBlliZgt-O which the device willrespond without altering the time limit.

The object of my invention is to provide a simple thermostatic timelimit device for circuit breakers which will permit the breaker to bereset immediately after hav- 5 ingbeen tripped, in which the amount ofcurrent required to operate the device ,and the time limit of operationmay be independently varied; and in which the dithculties anddisadvantages heretofore encountered in using hot wires or other thermalexpansion devices are avoided.

In carrying out my invention I provide an actuating-means for thecircuit controller, which is preferably a hot wire, an expansion bar orany equivalent arrangement requiring a predetermined time to move to aposition in which it can operate the controller, and a restraining meansor detent to mamtain the actuating means in an inoperative pos1t1onunless a variation of current of predetermined amount takes place,whereupon the -detent instantly leaves .the actuating means free toactuate the controller if the variation of current persists forasufficient length of time As soon as the current returns to normal thedetent returns to position to maintain the actuating means inoperative,so that when the current becomes normal the controller can be reset andwill beheld closed regardless of the temperature of the expansion barwhich actuates the controller.

A gradual elongation of the eX-.

pansion bar due to a continued fiow of current less than that for whichthe device is set cannot trip the controller since the expansion bar isunable to affect the controller until released by the restraining meansas a result of abnormal current.

My invention will best be understood in connection with the accompanyingdrawings which illustrate one embodiment of my in- .vention and inwhicha Figure l is a view of a device embodying my'invention applied toa circuit breaker, the parts being shown in the position as sumed bythem when normal current is flowing, and Fig. 2 a view of the samedevice with the parts in the position assumed by them to-trip thecircuitbreaker.

in the arrangement shown in the drawings. the circuit to be cont-rolledcomprises leads 1 and 2, one of which is connected to a circuit breaker3 by means oft which the cir cuit may be opened when desired. Thecircuit breaker is provided with a tripping coil +t which may beenergized from the main circuit through leads 5 and 6 and when energizedtrips the circuit breaker and thereby opens the main circuit.

The arrangement shown in the drawings proportioned that it for securinga time limit comprises an ex ansion bar or hotwire 7 connected in serieswith the lead 2 of the main circuit, and so will require a predeterminedtime to respond to a predetermined excess of current and move from aninoperative "position to an operative position. The

cooperating with an adjustable contact 12 connected to the lead'5. \Vhenthe expansion bar 7 moves the tripping means or arm 9 to operativeposition and brings the contacts 11 and 12into engagement, the circuitthrough the'tripping coil'4 is closed, since the lead 6 is connected tothe contact-making arm 9 through a flexible coil 13, and the circuitbreaker is tripped. The contact 12-is adjustably mounted in a support14, and its position is controlled by ail-adjusting screw 15 mounted insaid support. The osition of the contact 12 is indicated by a pointer 16carried thereby and cooperating with a scale on the support 14. The timelag or period of time whichelapses from the occurrence of an abnormalcurrent and the beginning of the heating of the strip-7 until thecontacts 11 and 12 engage and the circuit breaker 3 is tripped is variedby changing the position of the contact 12.

So far as described the device is an ordinary tripping mechanism havinga single hot wire and with the disadvantages 1nherent1,ih sucl1 adevice. In order to overcome tlifose disadvantages I mount upon the base8 s restrainii'i'g means for the tripping mechanism of any suitabletype, and shown as a pivoted detent 17 with one end normally held inposition by a spring 18 to engage a notch in a locking member 19 rigidlyconnected to the tripping means or contactmaking arm 9 and thereby holdsaid arm in the inoperative position shown in Fig. .1. When the detentis in engagement with the a member 19 the actuation of the contactmakingarm 9 and therefore the tripping of 1 the circuit breaker 4 isprevented, since the contact-making arm is held stationary regardless ofthe temperature of the expansion strip 7 and 1f the expansion stripbecomes heatedunder such conditions it can "assume the form shown by thedotted line in Fig. .1, but Without moving the arm 9 to operativeposition. The restraining means or detent 17 is controlled'by any devicewhich will respond instantly to variations of current in the maincircuit, and the arrangement which I prefer comprises a hot Wire 20 ateach end in any suitable way upon a base plate 8,

of such a size that it responds practically instantaneously to changesin current. This wire is stretched between two rigid supports on thebase 8 and at the middle is engaged by the short arm of abell-erankcontrolling lever 21 pivotally mounted on the base 8 and compelled toremain in engagement with the wire 20 by a spring 22. It may be placedin shunt to bar 7 so as to carry a small fractional part of the current.The controlling arm affects the restraining means or detent 17 throughan adjustable set-screw 23 so mounted on the controlling arm that itwill engage the end 24 of the detent 17 when the current in the maincircuit reaches a predetermined amount and move the detent to releasethe contact-making arm 9. By varying the adjustment of the set-screw 23the amount of current which must flow in the main circuit before thedetent is actuated may be varied, and this adjustment does not afl'ectin any way the time limit of the device, which isdetermined by theposition of the contact 12 with relation to the contact 11. If desiredthe end of the controlling arm 21 may be formed as a pointer tocooperate with a scale on the support 14 to indicate the amount ofcurrent flowing in the circuit.

The operation of the device is as follows: When the current in the maincircuit is normal the parts are in the position shown in Fig. 1, and anyslight variations in temperature of the expansion bar 7 .has no effecton the contact-making arm because that arm is positively restrained bythe latch 17. Moreover the bar 7 is relatively to the wire, so verythick, that it will expand slowly or with atime interval. If an abnormalcurrent flows in the main circuit, the wire 20 instantly expands andsags down to the position shown in Fig. 2, in which position theset-screw 28 engages the end 24 of the detent 17, moving the detent outof engagement. with the member 19 and leaving the contactmaking arm 9free to respond to movement of the expansion bar 7.. As the abnormalcurrent continues, the expansion bar bows up into the form shown in Fig.2 moving the arm 9 toward operative position, and eventually thecontacts 11 and 12 engage, completing the circuit through the trip coil4 andbreaking the main circuit by opening the circuit breaker 3. If thecurrent returns to normal before the contacts 11 and 12 .have come intoengagement, the controlling arm 21 moves back to the position shown inFig. 1 and the detent 17 is held by its spring 18 in a position to catchand engage the member 19 as soon as the contact-making" arm is returnedto normal position by the cooling down of the expansion bar. When thecircuit breaker is tripped, the current in the main circuit ceases andthe hot wire 20 immediately returns to its normal position shown in Fig.1,

Ybri 'ng the detent 17 into position to catch breaker-3 immediately isto forcibly return the contact-making arm 9 to its position against theforce exerted by the hot expansion strip 7, whereupon the contact-makingarm will be caught by the detent 17 and positively held in theinoperative position shown in Fig. 1, regardless of the temperature ofthe strip 7 unless another abnormal flow of current affects the .wire 20and thereby causes the detent 17 to release the contact-making arm 19.

My invention may be embodied in many other forms than that shown anddescribed, and other equivalent devices may be'substituted for the hotwire. I therefore do not wish to be restricted to the precise form shownbut intend to cover by the appended claims'all changes and modificationswithin the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, 1s, t

1. The combination with a current 0011- trolling device, of actuatingmechanism responsive with a time la to variations of current foraffecting sai device to control the circuit, a detent engaging saidactuating mechanism to render it inoperative when the current isnormaland means responsive to abnormal current for moving the detent torelease said mechanism.

2. The combination with a circuit breaker, of a thermostatic'device oflarge current carrying capacity for actuating the tripping mechanism ofsaid breaker, and a second thermostatic device of small capacity andquick to cool for controlling the tripping action of said first device.

3. The combination with a circuit breaker, of a thermostatic strip oflarge section for actuating the tripping mechanism of said breaker, anda second thermostatic strip of, small section for controlling thetripping aclion of said first strip. v

4. The combination with a current controlling device of a thermostaticactuating mechanism responsive to current for aflecting said controllingdevice and movable to inoperative position while hot. a detent forlocking said device in inoperative position, and means responsive tocurrent for controlling the detent. v

5. The combination with a current conrollillg device of a thermostaticactuating ing said controlling device and movable to inoperativeposition while hot, a detent for and means for holding thedetent out oflocking position whilean abnormal current is flowing.

6. In a circuit controller, the combination with tripping means for thecontroller, of a thermostatic device slowly responsive to curping means,a detent for holding the trip in inoperative position, and a secondthermostatic device quickly responsive to current in thecircuit forcontrolling said detent.

7. In a circuit controller, the combination with tripping means for thecontroller. of a thermostatic device slowly responsive to current in thecircuit for operating said tripping means and movable to inoperativeposition While hot. a detent for holding said device ininoperativeposition, and a second thermostatic device quickly responsive to currentin the circuit foncontrolling said detent.

8. In a circuit controller, the combination with trippingmeans for thecont-roller, of a thick expansion strip connected in the circuit with afree portion in engagement with the tripping means to actuate the same,a detent for holding said strip in inoperative position, and a thinexpansion strip conto release the thick strip when an abnormal currentflows 1n the circuit.

with tripping means for the controller slowly responsive to abnormalcurrent, of a detent t'or positivelyholding said tripping means ininoperative position, controlling means quickly responsive to variationsof current for moving the detent to release the tripping means, andadjustable means for varying the relation of said controlling means tothe'detent.

In a circuit controller, the combina- Hutton with tripping means slowlyresponsive to abnormal current, of a detent for positively holding saidtripping means in inoperative position, controlling means quicklyresponsive to variations in current, and an adjustable stop carried bysaid controlling release the tripping means.

my hand this sixth day of August 1907. I'VILHELM FELLENBERG.

Witnesses:

JULIUS RUMLANI),

mw'lmillsm responsive to current for affect- A LFRED Worm.

locking said device in inoperative position,

nected in the circuit for moving the detent- 9. In a circuit controller,the combination In witness whereof, I have hereunto set rent .in thecircuit for operating said trip- I means for engaging the detent to moveit to

